Hmmm... £350 seems a lot for that piece of pipe, you can usually get a full cat-back system for about that price! And although they'll be happy to help with any software upgrades you need, there's no mention of how much they'll charge for their help

And seeing how much soot is produced on diesel cars without a DPF, I don't know how easily they'd pass an MOT soot test.

Hmmm... £350 seems a lot for that piece of pipe, you can usually get a full cat-back system for about that price! And although they'll be happy to help with any software upgrades you need, there's no mention of how much they'll charge for their help

And seeing how much soot is produced on diesel cars without a DPF, I don't know how easily they'd pass an MOT soot test.

For the sake of a few BHP, a remap has to be a better option?

+1
I wouldn't want an extra 5-10 bhp if my car is chugging out black smoke.
Just get a remap

And a +1 from me. How can you get 5-10mpgm, which means up to about 20pc better fuel economy? Ain't gonna happen. If it were going to happen, why haven't they provided any details of any tests where they determined they got a 20pc improvement.

If it were even possible to get 20pc, why haven't BMW redesigned the DPF. The answer is this 'fuel saving' is pulled out of the air.

I think the key is in the wording they've used... You could see an increase in BHP if you have a faulty DPF and replace it with their decat pipe. Chances are, you'd see a similar improvement by just replacing the DPF with a working one.

Aftermarket exhausts can see power increases, but you'd need a full turbo back system and you'd probably only see a few bhp anyway.

Having owned a DPF-equipped car in the past, and being stuck with a non-DPF shitheap now, I'm VERY conscious of how much smoke I leave behind me when I put my foot down. I'd rather have the DPF fitted, to be completely honest.

I know that the mpg claims may seem outlandish but we have taxi's and fleet vehicles running our envirotune software reporting these figures daily.

The adverts states, "You will experience a 5-10 mpg improvement over the original DPF depending on your driving style and software selection"

Please allow me to explain and I will update our website with a clearer explanation after reading your feedback -

The DPF regen process injects fuel into the cylinder whilst the exhaust valves are open, this unburned diesel ignites within the DPF creating the furnace that converts the collected soot into ash.

The maps in the engine management responsible for this process we call the "post injection maps". When this process is disabled you immediately enjoy improved consumption as the engine is no longer sending fuel through the exhaust.

Disabling the post injection maps are not the only reason you enjoy improved consumption.

The engine in question here is the M57N2 and in this application removal of the DPF drops the exhaust gas temperature by around 45°c which results in much cooler running exhaust valves, manifold and turbocharger, this of course has a direct effect on the intake charge temperature resulting in more air at any given rpm and the turbo charger spools more dianamically and earlier offering increased oxygen in low rpms.

The drop in EGT's opened up many windows during software development and we were able to inject the fuel much earlier allowing the same amount of fuel more time to burn releasing more energy and carefull adjustments to the rail pressure provided an improved spray pattern with slightly increased injection quantity offering the increase in performance with more complete combustion. The egr map is tuned to close much earlier further increasing the cylinder oxygen content.

I should also add that when you remove the DPF an a BMW diesel, the car remains visibly smokeless until the car attempts a regen where the vehicle will emit grey/white smoke which is unburned diesel.

Our software upgrades with DPF OFF are also smokeless. If you fit the pipe without software then the car will continue to attempt a regen, report DPF failure and you will experience the smoke not to mention low rpm turbine instability.

I frequent many forums and those who know me also know that I am happy to answer any questions relating to our products. There is absolutely no attempt to mislead and we are as excited as our customers if not more by our developments. We are delighted that BMW left a window of opportunity to further improve on what is a remarkable piece of engineering.

The complete kit is available here which includes a choice of two software upgrades however when coming to our workshop in Glasgow or to our appointed dealer in Chelmsford PMW the software upgrade costs £399 including VAT.

M57N - £60 - two part kit, decat and dpf and can be done on your driveway if you have reasonable mechanical skills. Takes 1hr 30mins in our workshop.

We generally offer three software levels on a customers car, Envirotune which is focussed on economy and emissions though does provide a performance increase, Ecotune which is the best balance between performance and economy(dyno print attached) and Maxitune which is focussed on the maximum safe performance of the vehicle considering the limitations of the hardware.

I love how people just disregard an discredit things without knowing one iota what they are talking about. At least read up about the topic before discrediting a companies product for gods sake and provide a balanced argument as to why it wouldn't work. A simple 'why would BMW make a DPF when they could make one 10% more fuel efficient' isn't good enough because there are many things BMW scrimp an save on that can be improved on just look at remaps which improve on power and economy. BMW leave room for improvement all over the place and this company are trying to exploit that.

As for those 'shitheaps' without DPF kicking out black soot I can categorically tell you that as an owner of a 'shitheap' my car does not kick out any soot that is visible to the naked eye. This is due to spending that little bit extra on decent fuels that contain less crap which therefore produces less crap at the end. If you use cheap fuel you pay the price an clearly you do.